Thread: DCT tranny
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      11-30-2012, 08:38 PM   #25
Major General

Drives: 340i M-sport AT
Join Date: Mar 2006
Location: Chicago

iTrader: (1)

Originally Posted by NISFAN View Post

You make a big deal about being able to skip gears on a downshift, and I don't refute your information on what gearboxes can and can't.

The question I have is why? Why would you need to downshift 3-4 gears in an instant unless you had fallen asleep at the wheel?

I have driven large braked, sticky tyred M3's on track (DCT versions), stamping on the brakes at the end of the straight going from 6th to a 2nd gear corner, and have never thought 'Jeez this gearbox needs to change down quicker'
It's a great question.

I think that ZF used that information as a way to plug and differentiate how good the AT is.

IN real day to day driving the only advantage I'd say there is is that on multi-gear downshifts it will do 3 gears down and shift only once.
It's practical because of how controlled it is, so there is less chassis motion while coming into a turn, the car settles down quicker before the turn.

Again, I'm only giving information I've gleamed.
I can only speak about how good it is from an AT point of view as I am mainly an MT driver.
For as good as this AT is I still can't put it in the gear I want directly as I can with a MT. With a MT I can go from 6th to 2nd in one motion.
With my AT I have to be really quick on the paddles or lever to hit it 4 times. Going from 8 to 2, I don't think anyone can do it as the trans would start shifting before we could move the paddles/lever 6 times.

How this trans works is worth discussion.
How fast it can skip 6 gears is more about marketing and bragging, imo.